FIG. 7 is a block diagram illustrating an idle stop system having a conventional in-vehicle power source device. As illustrated in the drawing, an idle stop controller 1 inputs signals from a vehicle speed sensor 2, an idle stop prohibiting switch 3, a brake switch 4, a brake pressure sensor 5, an engine water temperature sensor 6, an engine hood switch 7, a seat belt switch 8, a driver seat door switch 9, a mission shift position sensor 10, an axel opening sensor 11, a battery temperature sensor 12 for a first power source, a battery current sensor 13 for the first power source, and a battery voltage sensor 14 for the first power source, wherein the first power source is a lead battery. The idle stop controller 1 also inputs signals of state of charge and temperature of a second power source from a battery management unit 15 for the second power source, which is a secondary battery, and controls the battery management unit 15. Moreover, the idle stop controller 1 controls an engine controller 16, a hill holding valve 19, an oil pump 20, an indicator 21, and a starter 22. Furthermore, the engine controller 16 controls an injector 17 and an alternator 18. The in-vehicle power source device having the first power source and the second power source supplies power to the idle stop controller 1. Furthermore, the idle stop controller 1 monitors states of the first power source and the second power source, and determines whether idle stop is possible.
FIG. 8 illustrates a power source system of the conventional in-vehicle power source device. As illustrated in the drawing, a first electric load 31, a first power source 32, which is a lead battery, an alternator 33, a second power source 34, which is a secondary battery, and a second electric load 35 are connected in parallel. A first fuse 36 is connected between the first electric load 31 and the first power source 32. A second fuse 37 is connected between the first electric load 32 and the alternator 33. A third fuse 38 and a battery selector switch (SW) 39 are connected in series between the alternator 33 and the second power source 34. A fourth fuse 40 is connected between the second power source 34 and the second electric load 35. A normally closed-type bypass relay 41 is connected in parallel to the battery selector switch 39. A main relay 42 is connected between the second power source 34 and the fourth fuse 40 (the second electric load 35). A battery pack 43 includes the second power source 34, the battery selector switch 39, the fourth fuse 40, the bypass relay 41, and the main relay 42. The second power source 34, the battery selector switch 39, the fourth fuse 40, the bypass relay 41, and the main relay 42 are stored in a case 44 of the battery pack 43.
Operations of the in-vehicle power source device illustrated in FIG. 8 will be explained with reference to FIG. 9.
In an operation 1, the battery selector switch 39 is turned on (ON), the bypass relay 41 is opened (OPEN), and the main relay 42 is turned off (OFF). In this state, the first power source 32, the alternator 33, and the second electric load 35 are connected, but the second power source 34 and the alternator 33 are not connected. Changing to this state is done when wishing to charge the first power source 32 right after starting an engine, for example, or when putting the alternator 3 in a non-power generation state, and supplying power to the first electric load 31 and the second electric load 35 only from the first power source 32.
In an operation 2, the battery selector switch 39 is turned on (ON), the bypass relay 41 is opened (OPEN), and the main relay 42 is turned on (ON). In this state, the first power source 32, the alternator 33, the second power source 34, and the second electric load 35 are connected. Changing to this state is done when storing electric energy generated by the alternator 33 in the second power source 34 during regenerative deceleration, etc.
In an operation 3, the battery selector switch 39 is turned off (OFF), the bypass relay 41 is opened (OPEN), and the main relay 42 is turned on (ON). In this state, the first electric load 31, the first power source 32, and the alternator 33 are connected, and the second power source 34 and the second electric load 35 are connected. Therefore, the electric energy stored in the second power source 34 can be supplied to the second electric load 35. Changing to this state is done when wishing to supply power to the second electric load 35 only from the second power source 34, so as to reduce a generating load on the alternator 33 and improve fuel consumption during normal running or idling stop.
In an operation 4, the battery selector switch 39 is turned off (OFF), the bypass relay 41 is closed (CLOSE), and the main relay 42 is turned off (OFF). In this state, the first electric load 31, the first power source 32, the alternator 33, and the second electric load 35 are connected. Note that the first electric load 31, the first power source 32 and the alternator 33 are connected to the second electric load 35 via the bypass relay 41. Changing to this state is done when supplying dark current to the second electric load 35 from the first power source 32 when the ignition switch (SW) is off, etc. Changing to this state is done when the battery pack 43 becomes abnormal.